#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>
#include<math.h>
int main(int argc, char* argv[])
{
	long long int k = 7385137888721 * 4 + 10470245;
	long long int m = (long long int)sqrt(k);
	printf("%lld", m - 1);
	return 0;
}